The advent of global communications networks such as the Internet and rapid advance in cellular communications are converging to meld both environments. Thus, cellular users can access IP networks (or packet networks) and all the services provided therein. SIP (session initiation protocol) is a signaling protocol used for establishing sessions in an IP packet network. A session could be a simple two-way telephone call or it could be a collaborative multi-media conference session.
GPRS (General Packet Radio Service) and UMTS (Universal Mobile Telecommunications System) standards provide a way of establishing data connectivity between mobile devices, according to one standard termed ME/UE (mobile equipment/user equipment), and packet networks using a PDP (packet data protocol) context activation procedure. As part of the negotiation, a certain level of QoS (quality-of-service) can be negotiated for the connection being configured. UMTS network services have different QoS classes for at least four types of traffic, including a conversational class (e.g., voice, video telephony, video gaming), a streaming class (e.g., multimedia, video on demand, webcast), interactive class (e.g., web browsing, network gaming, database access), and background class (e.g., email, SMS-short message service, downloading).
For a GPRS network, the allowed QoS is usually pre-provisioned in the HLR (home location register) on a per-subscription basis and is fixed, since there is limited QoS support available. The HLR is the database within a GSM (Global System for Mobile Communications) network which stores all the subscriber data.
Contrariwise, UMTS supports various types of connectivity with different levels of QoS flow specifications. Negotiation of different QoS channels involves either establishing a new PDP context or by modifying the current context. Due to limitations in usability and practicality, modification of the existing context and its associated QoS is seldom done. Instead, the UE will negotiate a new context each time a new QoS is required. The standards provide an efficient way of allowing the UE to configure connectivity with the required QoS support. This is done via a secondary PDP context activation procedure.
For UE running on an embedded platform, such as a handset, the mechanism of establishing new PDP context based on the needs from an application is highly integrated, and can be done seamlessly, since both the underlying stack and the applications run on the same platform. This is more difficult for UE in a PC card form factor, since the stack and the applications run on two heterogeneous platforms. Due to this limitation, the PC (personal computer, or more generally, computing device) can only set up one PDP context (a primary context) either by using a generic point-to-point connection (e.g., dial-up networking (DUN)) via a virtual modem port, or one LAN-like interface via a network interface. Currently there is only one connection type possible for all applications running on the PC, thus preventing applications from using multimedia services (e.g., IMS-IP multimedia subsystem). All applications will then need to use the same QoS that is associated with that single context. This prohibits the UMTS PC card users from obtaining concurrent multi-QoS support tailored to different applications.